Effects of surgical masks on droplet dispersion under various oxygen delivery modalities

Takazono, Takahiro; Yamamoto, Kazuko; Okamoto, Ryuta; Morimoto, Shimpei; Izumikawa, Koichi; Mukae, Hiroshi

doi:10.1186/s13054-021-03512-w

Cited by 19 publications

(33 citation statements)

References 3 publications

(3 reference statements)

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“…Our results generally agree with recent studies that indicate that HFNC does not lead to significantly increased aerosol dispersal compared to LFNC in a group of healthy adults [7][8][9]11]. The large spread in individual aerosol dispersal among the 20 subjects (Figure 2), despite measures to reduce confounders and background noise, indicates that there are strong individual factors influencing aerosol dispersal.…”

Section: Discussionsupporting

confidence: 92%

“…Several recent approaches have investigated aerosol dispersal and spread during oxygen therapies and research is still ongoing to answer these questions [7][8][9][10][11][12][13]. While the present evidence is non-conclusive if HFNC or NIV oxygen treatment has high aerosol dispersal potential, results from recent studies suggests that HFNC and NIV does not lead to significantly increased aerosol dispersal compared to low-flow oxygen modalities [14][15][16][17].…”

Section: Introductionmentioning

confidence: 62%

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Quantification of aerosol dispersal from suspected aerosol-generating procedures

et al. 2021

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BackgroundOxygen delivering modalities like humidified high-flow nasal cannula (HFNC) and non-invasive positive-pressure ventilation (NIV) are suspected of generating aerosols that may contribute to transmission of disease such as COVID-19. We sought to assess if these modalities lead to increased aerosol dispersal compared to the use of non-humidified low-flow nasal cannula oxygen treatment (LFNC).MethodsAerosol dispersal from 20 healthy volunteers using HFNC, LFNC and NIV oxygen treatment was measured in a controlled chamber. We investigated effects related to coughing and using a surgical facemask in combination with the oxygen delivering modalities. An aerodynamic particle sizer measured aerosol particles (APS3321, 0.3–20 µm) directly in front of the subjects, while a mesh of smaller particle sensors (SPS30, 0.3–10 µm) was distributed in the test chamber.ResultsNon-productive coughing led to significant increases in particle dispersal close to the face when using LFNC and HFNC but not when using NIV. HFNC or NIV did not lead to a statistically significant increase in aerosol dispersal compared to LFNC. With non-productive cough in a room without air changes, there was a significant drop in particle levels between 100 cm and 180 cm from the subjects.ConclusionsOur results indicate that using HFNC and NIV does not lead to increased aerosol dispersal compared to low-flow oxygen treatment, except in rare cases. For a subject with non-productive cough, NIV with double-limb circuit and non-vented mask may be a favourable choice to reduce the risk for aerosol spread.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 62%

Quantification of aerosol dispersal from suspected aerosol-generating procedures

et al. 2021

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“…Studies of healthy volunteers measuring aerosol particle concentrations have not found any increase in aerosol production comparing HFNC at various flows to NIPPV, conventional nasal cannula, or breathing room air [ 92 , 93 ]. Photographic particle visualization studies in healthy volunteers using scattering light as well as chemical marker deposition likewise have not demonstrated a relationship between increasing flow and particle formation [ 94 , 95 ]. However, laser aerosol spectrometry in healthy volunteers has demonstrated flow-dependent increases in production of small and large aerosol particles [ 96 ].…”

Section: Discussionmentioning

confidence: 99%

“…As aerosol generation can vary with individual breathing patterns, HFNC should also be viewed from the perspective of aerosol dispersion [ 93 , 98 ]. Coughing has been associated with significantly increased numbers of aerosol particles emitted from healthy volunteers [ 93 , 94 , 99 ]. In a simple study using visible food dye, healthy volunteers asked to cough generated droplets that spread a mean distance of 2.5 m at baseline and 2.9 m with HFNC at 60 L/min, with a maximum distance of 4.5 m observed for the latter [ 100 ].…”

Section: Discussionmentioning

confidence: 99%

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High flow nasal cannula for adult acute hypoxemic respiratory failure in the ED setting

Long

Liang

Lentz

2021

The American Journal of Emergency Medicine

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Generation of Aerosols by Noninvasive Respiratory Support Modalities

Zhang,

Lilien,

van Etten-Jamaludin

et al. 2023

JAMA Netw Open

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ImportanceInfection control guidelines have historically classified high-flow nasal oxygen and noninvasive ventilation as aerosol-generating procedures that require specialized infection prevention and control measures.ObjectiveTo evaluate the current evidence that high-flow nasal oxygen and noninvasive ventilation are associated with pathogen-laden aerosols and aerosol generation.Data SourcesA systematic search of EMBASE and PubMed/MEDLINE up to March 15, 2023, and CINAHL and ClinicalTrials.gov up to August 1, 2023, was performed.Study SelectionObservational and (quasi-)experimental studies of patients or healthy volunteers supported with high-flow nasal oxygen or noninvasive ventilation were selected.Data Extraction and SynthesisThree reviewers were involved in independent study screening, assessment of risk of bias, and data extraction. Data from observational studies were pooled using a random-effects model at both sample and patient levels. Sensitivity analyses were performed to assess the influence of model choice.Main Outcomes and MeasuresThe main outcomes were the detection of pathogens in air samples and the quantity of aerosol particles.ResultsTwenty-four studies were included, of which 12 involved measurements in patients and 15 in healthy volunteers. Five observational studies on SARS-CoV-2 detection in a total of 212 air samples during high-flow nasal oxygen in 152 patients with COVID-19 were pooled for meta-analysis. There was no association between high-flow nasal oxygen and pathogen-laden aerosols (odds ratios for positive samples, 0.73 [95% CI, 0.15-3.55] at the sample level and 0.80 [95% CI, 0.14-4.59] at the patient level). Two studies assessed SARS-CoV-2 detection during noninvasive ventilation (84 air samples from 72 patients). There was no association between noninvasive ventilation and pathogen-laden aerosols (odds ratios for positive samples, 0.38 [95% CI, 0.03-4.63] at the sample level and 0.43 [95% CI, 0.01-27.12] at the patient level). None of the studies in healthy volunteers reported clinically relevant increases in aerosol particle production by high-flow nasal oxygen or noninvasive ventilation.Conclusions and RelevanceThis systematic review and meta-analysis found no association between high-flow nasal oxygen or noninvasive ventilation and increased airborne pathogen detection or aerosol generation. These findings argue against classifying high-flow nasal oxygen or noninvasive ventilation as aerosol-generating procedures or differentiating infection prevention and control practices for patients receiving these modalities.

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Effects of surgical masks on droplet dispersion under various oxygen delivery modalities

Cited by 19 publications

References 3 publications

Quantification of aerosol dispersal from suspected aerosol-generating procedures

Quantification of aerosol dispersal from suspected aerosol-generating procedures

High flow nasal cannula for adult acute hypoxemic respiratory failure in the ED setting

Generation of Aerosols by Noninvasive Respiratory Support Modalities

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