Variation in Aerosol Production Across Oxygen Delivery Devices in Spontaneously Breathing Human Subjects

Abstract

We sought to assess whether HHFNC results in greater production of aerosolized particles than 6 liters per minute nasal cannula, using state-of-the-art techniques of aerosol measurement, in spontaneously breathing human volunteers in a simulated hospital room. For each volunteer, we first measured background aerosol levels in the room immediately prior to testing. We then measured aerosol levels while the healthy volunteer laid in bed - - with the head of bed at 30 degrees - - wearing the following oxygen delivery devices: (a) 6L/min nasal canula (NC) with humidification; (b) non-re-breather mask (NRB) with 15L/min gas flow, non-humidified; (c) HHFNC with 30L/min gas flow; (d) HHFNC with 60L/min gas flow. Two scanning mobility particle sizing (SMPS) systems (TSI 3080/3030, TSI 3080/3750) were used to measure aerosols 10 to 500 nanometer (nm) in size for each of the oxygen delivery devices. There was no variation in aerosol level within patients between room air, 6 L/min NC, 15 L/min NRB, 30 L/min HHFNC, and 60 L/min HHFNC, regardless of coughing.

High-flow nasal cannula for acute hypoxemic respiratory failure in patients with COVID-19: systematic reviews of effectiveness and its risks of aerosolization, dispersion, and infection transmission

“…We identified 3,523 unique citations using our electronic searches, 26 pre-prints from medRxiv, and one additional citation suggested by an expert panelist. We completed full-text review of 33 potentially eligible studies and included six studies, [53][54][55][56][57][58] and identified one additional study through reference list screening, 59 for a total of seven eligible studies (Fig. 9).…”

“…9). [53][54][55][56][57][58][59] Of the seven eligible studies, six were simulation studies [53][54][55][57][58][59] and one was a crossover study. 56 No studies directly evaluated risk of aerosol generation or infection transmission associated with HFNC use among patients with COVID-19.…”

“…56 No studies directly evaluated risk of aerosol generation or infection transmission associated with HFNC use among patients with COVID-19. Three simulation studies included healthy adult volunteers, 54,58,59 and three included a model patient simulator. 53,55,57 The crossover study included 19 critically ill adult patients who received supplemental oxygen therapy and crossed over to HFNC.…”

The Impact of High-Flow Nasal Cannula Use on Patient Mortality and the Availability of Mechanical Ventilators in COVID-19

“…With infectious pathogens with droplet or airborne spread, concern exists about potential exposure risk associated with using HFNC. However, newer evidence should alleviate this worry (33,34) and, as such, institutions who initially disallowed use of HFNC for COVID-19associated respiratory failure have begun to permit it. (35) In the context of a pandemic such as COVID-19, our priorities must shift slightly.…”

Extubation success without using high-flow nasal cannula and non-invasive ventilation for patients with coronavirus disease 2019 (COVID-19): A retrospective observational study

“…Some reports suggest that the use of HFNC and NIV in patients with COVID-19 should be discouraged because of the risk of aerosol generation and exposure of health care workers [15][16]. Although no studies have directly evaluated the risk of aerosol generation or infection transmission associated with HFNC and NIV use in patients with COVID-19 [17][18][19][20][21][22][23][24], the use of NPPV and HFNC aggravates this risk through continuous open circuit viral aerosolization. If the patient is not in a negative pressure room, viral shedding through aerosol generation can extend beyond the room, thereby contaminating the hallways and beyond.…”