Particle dispersion investigative research
The potential risk posed to HCWs by infectious patients has heightened research interest in the dispersion of exhaled particles which may increase risk of nosocomial infection.
Publication
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Title
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Journal
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From Conclusion/Discussion
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Gershengorn et al. 2020.1 |
The Impact of High-Flow Nasal Cannula Use on Patient Mortality and the Availability of Mechanical Ventilators in COVID-19. |
Annals of the American Thoracic Society |
“... institutions who initially disallowed use of [NHF] for COVID-19-associated respiratory failure [due to potential risk of exposure] have begun to permit it.” |
Gaeckle et al. 2020.11 |
Aerosol Generation from the Respiratory Tract with Various Modes of Oxygen Delivery. |
American Journal of Respiratory and Critical Care Medicine |
“...in healthy individuals, [NIV] or HFNC did not produce higher-concentration aerosol from the respiratory tract than room air or nonhumidified oxygen conditions. In fact, in some instances HFNC and [NIV] might decrease aerosol.” |
Iwashyna et al. 2020.12 |
Variation in Aerosol Production Across Oxygen Delivery Devices in Spontaneously Breathing Human Subjects. |
medRxiv Pre-print |
“... there was no evidence of increased [particles such as aerosols and droplets] with nasal cannula, non-rebreather mask, or heated high flow nasal cannula...” |
Jermy et al. 2020.13 |
Assessment of dispersion of airborne particles of oral/nasal fluid by high flow nasal cannula therapy. |
medRxiv Pre-print |
“NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing.” |
Kotoda et al. 2020.14 |
Assessment of the potential for pathogen dispersal during high-flow nasal therapy. |
Journal of Hospital Infection |
“... it is likely that high-flow nasal therapy does not increase the potential risk of droplet and contact infection.” |
Leung et al. 2019.15 |
Comparison of high-flow nasal cannula versus oxygen face mask for environmental bacterial contamination in critically ill pneumonia patients: a randomized controlled crossover trial. |
Journal of Hospital Infection |
“HFNC use in patients with Gram-negative pneumonia did not increase airborne and surface [Gram-negative bacterial] contamination compared to an oxygen mask, suggesting that additional infection control measures are not required when using HFNC...” |
Kaur et al. 2020.16 |
Practical strategies to reduce nosocomial transmission to healthcare professionals providing respiratory care to patients with COVID-19. |
Journal of Hospital Infection |
“... it is suggested that a surgical or procedure mask be worn by patients receiving HFNC.” |
Table 3. Particle dispersion from use of NHF on COVID-19 patients.
In addition to the data from publications on dispersion in Table 3, Hui et al. 2019 and Hui et al. 2014 compared a range of respiratory therapies and interfaces with a method for evaluating the dispersion of exhaled air using smoke and lasers to trace air movement from a human patient simulator. Collated air dispersion results from the two studies conducted by Hui et al.17,18 are illustrated in the chart below.
Changes in Exhaled Air Dispersion¶

¶ Dispersion distance data shown on the chart is combined from two studies conducted by the same authors.
The experiments were conducted in rooms with different configurations. Not all of the interfaces depicted were directly compared.