%0 Journal Article %A Reinout A. Bem %A Niels van Mourik %A Rozalinde Klein-Blommert %A Ingrid J.B. Spijkerman %A Stefan Kooij %A Daniel Bonn %A Alexander P. Vlaar %T Risk of aerosol formation by high flow nasal cannula treatment in critically-ill patients %D 2021 %R 10.4187/respcare.08756 %J Respiratory Care %P respcare.08756 %X Background: There is a persistent concern over the risk of respiratory pathogen transmission, including SARS-CoV-2, by formation of aerosols (a suspension of microdroplets and residual microparticles after evaporation) generated by high flow nasal cannula (HFNC) oxygen therapy in critically-ill patients. This concern is fueled by limited available studies on this subject. In the present study, we test our hypothesis that HFNC treatment is not associated with increased aerosol formation as compared to conventional oxygen.Methods: We used laser light scattering and a handheld particle counter to detect and quantitate aerosols in both healthy subjects, as well as adults with acute respiratory disease, including COVID-19, receiving HFNC versus conventional oxygen therapy.Results: The use of HFNC was not associated with increased formation of aerosols as compared to conventional oxygen therapy in both healthy subjects (n=3) and subjects with acute respiratory disease, including COVID-19 (n=17).Conclusion: In line with scarce previous clinical and experimental findings, this study indicates that HFNC itself does not result in overall increased aerosol formation as compared to conventional oxygen therapy. This suggests there is no increased risk of respiratory pathogen transmission by HFNC to health care workers. %U https://rc.rcjournal.com/content/respcare/early/2021/02/09/respcare.08756.full.pdf