Effect of nebuliser and patient interface type on fugitive medical aerosol emissions in adult and paediatric patients

Abstract

Background: Open circuit aerosol therapy is associated with the potential for fugitive emissions of medical aerosol. Various nebulisers and interfaces are used in respiratory treatments, including the recent consideration of filtered interfaces. This study aims to quantify fugitive medical aerosols from various nebuliser types, in conjunction with different filtered and non-filtered interfaces.

Methods: For both simulated adult and paediatric breathing, four nebuliser types were assessed including; a small volume jet nebuliser (SVN), a breath enhanced jet nebuliser (BEN), a breath actuated jet nebuliser (BAN) and a vibrating mesh nebuliser (VMN). A combination of different interfaces were used including filtered and unfiltered mouthpieces, as well as open, valved and filtered facemasks. Aerosol mass concentrations were measured using an Aerodynamic Particle Sizer at 0.8 m and 2.0 m. Additionally, inhaled dose was assessed.

Results: Highest mass concentrations recorded were 214 (177, 262) µg m^-3 at 0.8 m over 45-minute run. The highest and lowest fugitive emissions were observed for the adult SVN facemask combination, and the adult BAN filtered mouthpiece combination respectively. Fugitive emissions decreased when using breath-actuated (BA) mode compared to continuous (CN) mode on the BAN for the adult and paediatric mouthpiece combination. Lower fugitive emissions were observed when a filtered facemask or mouthpiece was used, compared to unfiltered scenarios. For the simulated adult, highest and lowest inhaled dose were 45.1 (42.6, 45.6)% and 11.0 (10.1,11.9)% for the VMN and SVN respectively. For the simulated paediatric, highest and lowest inhaled dose were 44.0 (42.4, 44.8)% and 6.1 (5.9, 7.0)% for the VMN and BAN CN respectively. Potential inhalation exposure of albuterol was calculated to be up to 0.11 µg and 0.12 µg for a bystander and healthcare worker respectively.

Conclusion: This work demonstrates the need for filtered interfaces in clinical and homecare settings to minimise fugitive emissions and to reduce the risk of secondary exposure to care givers.

Keywords: Bystander exposure; Fugitive medical aerosol emissions; Jet nebuliser; Secondary inhalation; Vibrating mesh nebuliser.