Infection prevention and control
The WHO outlines additional precautions that should be taken to protect healthcare workers during aerosol-generating procedures associated with an increased risk of transmission6. These procedures include tracheal intubation, noninvasive ventilation, tracheotomy, cardiopulmonary resuscitation, manual ventilation before intubation and bronchoscopy.
NHF is not specifically named by the WHO as an aerosol-generating procedure associated with an increased risk of transmission.6 However, there has been some uncertainty about the potential creation of aerosols from all forms of noninvasive respiratory support including NHF.
According to the WHO: “Because of uncertainty around the potential for aerosolization, HFO, NIV, including bubble CPAP, should be used with airborne precautions until further evaluation of safety can be completed.”4
Recent publications by Hui et al.7, Leung et al.8 and Hui et al.9 compared the application of NHF to a range of alternative therapies and interfaces and did not find an increased risk of transmission via air dispersion. Collated air dispersion results from two studies conducted by Hui et al.7, 9 are illustrated in the chart below.
Li et al.10 reviewed the existing literature and determined that dispersion via NHF shows a similar risk to standard oxygen masks. For resources in which the principle author of this paper discusses their findings in detail, visit The International Society for Aerosols in Medicine’s COVID-19 webpage.11
Ongoing research continues to investigate the risk of transmission of COVID-19 in the clinical setting.
*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.