Abstract
Background: Nebulization has been described as an aerosol generating procedure (AGP). AGPs may place health care workers at an increased risk of contracting viruses, such as COVID-19. No in vivo data are available on the fugitive aerosols generated by different nebulizers and interfaces, and the efficient modality to reduce the concentrations. This study aimed to explore the most effective method to reduce fugitive aerosol concentrations during nebulization.
Methods: This study was approved by the ethics committee in Rush University (20121804-IRB01). After signing consent, healthy volunteers were given treatments of 3mL saline using a small volume nebulizer (SVN) and vibrating mesh nebulizer (VMN) with a mouthpiece, a mouthpiece with filter, a mask, and a mask with scavenger in a random order for the 9 participants. An extra study was performed to compare the two scavengers (Exhalo vs Vapotherm) and a filter mask in a random order among 5 subjects. This study was implemented in an ICU room, with 2 particle sizers placed at 1 and 3 feet away from subjects. The aerosol concentrations at sizes of 0.3 to 10 µm were taken at baseline, before, during and after each treatment.
Results: Aerosol concentrations were higher with SVN than VMN. Regardless of nebulizer type, mask generated higher fugitive aerosol concentrations than mouthpiece. Adding a filter to mouthpiece reduced aerosol concentrations at particle sizes of 0.3 to 1.0 µm at 1 foot (all P <0.05) for VMN and at particle sizes of 0.3 to 3.0 µm (all P < 0.05) for SVN (Fig 1). Adding a scavenger over mask during nebulization reduced fugitive aerosol concentrations at particle sizes of 0.3 to 3 µm for both nebulizers. Regardless of the nebulizer type, both Vapotherm scavenger and filter mask had similar efficacy to reduce fugitive aerosol concentrations generated by nebulizer with mask (Fig 2).
Conclusions: SVN produced higher fugitive aerosol concentrations than VMN, while masks generated higher fugitive aerosol concentrations than mouthpiece. Adding a filter to mouthpiece or a scavenger to mask reduced fugitive aerosol concentrations for both SVN and VMN. Vapotherm scavenger and filter mask had similar effectiveness in reducing fugitive aerosol as mouthpiece with filter.
Figure 1. Mean aerosol concentrations of SVN vs VMN with mouthpiece and mask at 1 foot
Figure 2. Mean aerosol concentrations of SVN vs VMN with scavengers and filter mask at 1 foot
Footnotes
Commercial Relationships: Dr. Li discloses relationship with Fisher & Paykel Healthcare Ltd, Aerogen Ltd, and Rice Foundation and American Association for Respiratory Care. Dr. Fink discloses relationship with Aerogen Pharma Corp. Other authors have no conflict of interest to disclose.
Support: This study was supported by an unrestricted research funding from Aerogen Ltd.
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