Preliminary Findings on Control of Dispersion of Aerosols and Droplets During High-Velocity Nasal Insufflation Therapy Using a Simple Surgical Mask

Leonard, Scott; Atwood, Charles W.; Walsh, Brian K; DeBellis, Ronald J.; Dungan, George C.; Strasser, Wayne; Whittle, Jessica S.

doi:10.1016/j.chest.2020.03.043

Cited by 101 publications

(117 citation statements)

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“…Adding to previous simulations, these ANSYS results are considered more robust due to the higher mesh density (3.0 × 10 6 vs 8.8 × 10 5 ele-ments), finite mask thickness, improved mesh design, finer timesteps, better numerics, inclusion of lift effects, and more robust particle tracking. 20,23 This model suggests that the addition of a surgical mask, placed over the mouth and nose of the patient, may significantly reduce the spread of these particles by reducing the flow's velocity through the gaps, thereby decreasing the particles escaping into the room. An important finding was that the overwhelming majority of particles escaping the mask were associated with the model design of the simulation.…”

Section: F I G U R Ementioning

confidence: 99%

“…The preliminary simulation and model was published in a Chest Research Letter. 20 Upon review of this preliminary work, the authors designed a subsequent model, with the aim to provide a more reliable and accurate simulation. There are several differences between the preliminary study and the current study, which improve the simulation, and thereby provide more reliable findings.…”

Section: Major Technical Differences From the Preliminary Modelmentioning

confidence: 99%

“…A preliminary study was published with lower mesh-count and lower resolution. 20 This report provides a subsequent high-mesh-count simulation with improved fidelity, performed in ANSYS fluent CFD, of the noted models, thereby generating results with higher reliability/acuity than initially published.…”

Section: Introductionmentioning

confidence: 99%

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Reducing aerosol dispersion by high flow therapy in COVID‐19: High resolution computational fluid dynamics simulations of particle behavior during high velocity nasal insufflation with a simple surgical mask

et al. 2020

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Objective All respiratory care represents some risk of becoming an aerosol‐generating procedure (AGP) during COVID‐19 patient management. Personal protective equipment (PPE) and environmental control/engineering is advised. High velocity nasal insufflation (HVNI) and high flow nasal cannula (HFNC) deliver high flow oxygen (HFO) therapy, established as a competent means of supporting oxygenation for acute respiratory distress patients, including that precipitated by COVID‐19. Although unlikely to present a disproportionate particle dispersal risk, AGP from HFO continues to be a concern. Previously, we published a preliminary model. Here, we present a subsequent highresolution simulation (higher complexity/reliability) to provide a more accurate and precise particle characterization on the effect of surgical masks on patients during HVNI, low‐flow oxygen therapy (LFO2), and tidal breathing. Methods This in silico modeling study of HVNI, LFO2, and tidal breathing presents ANSYS fluent computational fluid dynamics simulations that evaluate the effect of Type I surgical mask use over patient face on particle/droplet behavior. Results This in silico modeling simulation study of HVNI (40 L min−1) with a simulated surgical mask suggests 88.8% capture of exhaled particulate mass in the mask, compared to 77.4% in LFO2 (6 L min−1) capture, with particle distribution escaping to the room (> 1 m from face) lower for HVNI+Mask versus LFO2+Mask (8.23% vs 17.2%). The overwhelming proportion of particulate escape was associated with mask‐fit designed model gaps. Particle dispersion was associated with lower velocity. Conclusions These simulations suggest employing a surgical mask over the HVNI interface may be useful in reduction of particulate mass distribution associated with AGPs.

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Section: F I G U R Ementioning

confidence: 99%

Section: Major Technical Differences From the Preliminary Modelmentioning

confidence: 99%

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Reducing aerosol dispersion by high flow therapy in COVID‐19: High resolution computational fluid dynamics simulations of particle behavior during high velocity nasal insufflation with a simple surgical mask

et al. 2020

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“…A surgical mask should be placed over the high-flow nasal cannula device to further reduce the risk of viral transmission. 2,8 3. What is the role of noninvasive positive pressure ventilation (NIPPV) measures for the patient with suspected or confirmed COVID-19?…”

Section: What Is High Flow Nasal Cannula and How Should It Be Started?mentioning

confidence: 99%

Just the Facts: What are the roles of oxygen escalation and noninvasive ventilation in COVID-19?

Long

Liang

Hicks

et al. 2020

CJEM

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A 37-year-old female presents with cough, fever, dyspnea, and myalgias for five days after recent contact with a family member with confirmed 2019 coronavirus disease . Her vital signs include T 38.3°C, HR 108, BP 118/ 70 mm Hg, RR 26 breaths per minute, and oxygen saturation 67% on room air. She is not in respiratory distress currently and is protecting her airway. Her chest X-ray reveals bilateral airspace opacities. You plan to immediately intervene and address her hypoxia. KEY CLINICAL QUESTIONS How can oxygen therapy be escalated to avoid intubation?Escalation of oxygen therapy includes a stepwise progression of devices meant to improve oxygenation and reduce patient work of breathing. 1-3 While this escalation may vary based on institution and local infection prevention policies, the basic strategy includes the following:

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Inoue¹,

Shirakawa²,

Fujita³

et al. 2020

Preprint

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Background In March 2020, the World Health Organization declared coronavirus disease 2019 (COVID-19) to be a global pandemic. It was also reported that approximately 20%-23% of patients with COVID-19 admitted to the hospital required mechanical ventilation (MV). Reintubation rates ranged from 13–19%, leading to increased mortality. Moreover, exposure of health care workers is a serious problem and intubation is a high-risk procedure because of aerosol generation. To reduce reintubation, preventive high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) after extubation are recommended. However, using HFNC and NIV in patients with COVID-19 may lead to the spread of infection. Without using HFNC and NIV, conventional spontaneous breathing trial (SBT) may overestimate a patient’s respiratory status. A highly demanding SBT accurately assesses a patient’s reserve capacity and may reduce reintubation. We did not use preventive HFNC or NPPV and extubated with a highly demanding SBT protocol. This study aimed to evaluate whether our protocol can be performed safely.Methods This single-centre study was conducted at the Kawasaki Municipal Hospital from February 2020 to June 2020. Patients with COVID-19 requiring MV were screened for their eligibility for the weaning procedure every day. Patients were extubated after administering methylprednisolone if SBT was well tolerated. SBT was performed with 3 cmH2O pressure support, 3 cmH2O positive end-expiratory pressure, and ≤ 0.30 fraction of inspired oxygen. In extubated patients, the reintubation rate, duration of MV, length of intensive care unit (ICU) and hospital stay, and rate of ventilator-associated pneumonia (VAP) were analyzed.Results Ten patients received MV. Two of 10 patients had no improvement in their respiratory status and did not qualify for the extubation criteria and died. Eight patients were extubated. No reintubations were performed (0%). The median durations of MV, ICU stay, and hospital stay were 13 (interquartile range [IQR], 10–16) days, 17 (IQR, 13–27) days, and 22 (IQR, 16–26), and 3 patients (37.5%) was diagnosed VAP.Conclusions Extubation was performed with a highly demanding SBT protocol, and no patients were reintubated. All patients did not require HFNC and NIV. Further research is required in critically ill patients.

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Preliminary Findings on Control of Dispersion of Aerosols and Droplets During High-Velocity Nasal Insufflation Therapy Using a Simple Surgical Mask

Cited by 101 publications

References 5 publications

Reducing aerosol dispersion by high flow therapy in COVID‐19: High resolution computational fluid dynamics simulations of particle behavior during high velocity nasal insufflation with a simple surgical mask

Reducing aerosol dispersion by high flow therapy in COVID‐19: High resolution computational fluid dynamics simulations of particle behavior during high velocity nasal insufflation with a simple surgical mask

Just the Facts: What are the roles of oxygen escalation and noninvasive ventilation in COVID-19?

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

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