RT Journal Article
SR Electronic
T1 Aerosol emission from the respiratory tract: an analysis of aerosol generation from oxygen delivery systems
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 276
OP 282
DO 10.1136/thoraxjnl-2021-217577
VO 77
IS 3
A1 Fergus W Hamilton
A1 Florence K A Gregson
A1 David T Arnold
A1 Sadiyah Sheikh
A1 Kirsty Ward
A1 Jules Brown
A1 Ed Moran
A1 Carrie White
A1 Anna J Morley
A1 AERATOR Group
A1 Bryan R Bzdek
A1 Jonathan P Reid
A1 Nicholas A Maskell
A1 James William Dodd
YR 2022
UL http://thorax.bmj.com/content/77/3/276.abstract
AB Introduction continuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) provide enhanced oxygen delivery and respiratory support for patients with severe COVID-19. CPAP and HFNO are currently designated as aerosol-generating procedures despite limited high-quality experimental data. We aimed to characterise aerosol emission from HFNO and CPAP and compare with breathing, speaking and coughing.Materials and methods Healthy volunteers were recruited to breathe, speak and cough in ultra-clean, laminar flow theatres followed by using CPAP and HFNO. Aerosol emission was measured using two discrete methodologies, simultaneously. Hospitalised patients with COVID-19 had cough recorded using the same methodology on the infectious diseases ward.Results In healthy volunteers (n=25 subjects; 531 measures), CPAP (with exhalation port filter) produced less aerosol than breathing, speaking and coughing (even with large >50 L/min face mask leaks). Coughing was associated with the highest aerosol emissions of any recorded activity. HFNO was associated with aerosol emission, however, this was from the machine. Generated particles were small (<1 µm), passing from the machine through the patient and to the detector without coalescence with respiratory aerosol, thereby unlikely to carry viral particles. More aerosol was generated in cough from patients with COVID-19 (n=8) than volunteers.Conclusions In healthy volunteers, standard non-humidified CPAP is associated with less aerosol emission than breathing, speaking or coughing. Aerosol emission from the respiratory tract does not appear to be increased by HFNO. Although direct comparisons are complex, cough appears to be the main aerosol-generating risk out of all measured activities.All data relevant to the study are included in the article or uploaded as supplemental information. Anonymised aerosol data from the AERATOR Study will be submitted to the Bristol data repository (data.bris.ac.uk) on completion of the full study.