Particulate generation with different oxygen delivery devices

Background: The Coronavirus pandemic has a high mortality rate in patients that are mechanically ventilated, which has led to an ever increasing interest in noninvasive forms of oxygenation. The use of these devices has the theoretical risk of increased exposure risk because of possible particulate generation. This study aimed to quantify the particulate generation associated with different oxygen devices. Methods: This was a prospective single center study conducted during September 2020 using ten healthy adult volunteers. Testing was conducted in a negative pressure hospital room using a light scattering particle counter. The oxygen devices used were a nasal cannula, an OxyMask™, a non-rebreathing mask, and a high flow system. Particle measurements were obtained at baseline in the room and then with each oxygen delivery device and pre-specified oxygen flow rates. These measurements were obtained different distances from the volunteer with their mouth open. A Wilcoxon/Kruskal-Wallis test was performed on each separate oxygen modality with all flow rates as one model. Results: The particle concentrations were slightly non-significantly increased with the OxyMask™ and non-rebreathing mask at the closest distance measured. As the distance increased, these counts decreased closer to ambient levels. The nasal cannula and high flow nasal cannula particle counts were not significantly different from ambient measurements at either distance. Conclusion: Nasal cannula, OxyMask™, non-rebreathing mask, and high flow oxygen did not generate any additional aerosols or droplets above a baseline room measurement, but further studies are necessary to determine infectious risk.