Nasal High Flow Therapy

How is COVID-19 being managed?

The WHO is issuing the following information on clinical management of patients and the status of the outbreak:

• Rolling updates on its COVID-19 web page²
• Interim guidance for Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected¹

The WHO refers to usage of Nasal High Flow therapy for pre-oxygenation prior to intubation and for non-invasive respiratory support with close monitoring for clinical deterioration in selected patients with hypoxemic respiratory failure.¹

Most of the clinical experience with COVID-19 patients currently comes from clinicians in China, South Korea and Italy. Although reports vary, they include the requirement for treatment of viral pneumonia and hypoxemia.

A retrospective observational study published by Yang et al.³ reported the clinical course and outcomes of critically ill patients with COVID-19 in Wuhan. 

A recent publication⁴ in the Chinese Journal of Critical Care & Intensive Care Medicine from a group in Wuhan describes their treatment approach, which includes Nasal High Flow.

Another recent publication by Xie et al.⁵ in Intensive Care Medicine gives recommendations based on measures taken in China to deal with the shortfall of critical-care resources.

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, non-invasive ventilation, tracheotomy, cardiopulmonary resuscitation, manual ventilation before intubation and bronchoscopy.

Nasal High Flow 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 Nasal High Flow.

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.” ¹

Recent publications Hui et al.⁸, Leung et al.⁹ and Hui et al.¹⁰ compared the application of Nasal High Flow to a range of alternative therapies and interfaces and did not find increased risk of transmission via air dispersion. Collated air dispersion results from two studies conducted by Hui et al.^{8, 10} are illustrated in the chart below.

Findings of a new study by Kotoda et al.¹¹ suggest that “high-flow nasal therapy does not increase the risk of droplet and contact infection”.
 

*Dispersion distance data shown on the chart is combined from two studies conducted by the same authors. 
Not all of the interfaces depicted were directly compared.